Any order placed through the web store — including orders placed by guests — must be associated with a Sage account and a price list. Otherwise, no pricing will appear on the web store and Sage will not be able to process the order.
To set the System Default Customer, go to System > Features, and select B2C from the drop-down menu. Next, scroll down to the Pricing & Stock Settings section.
In the screenshot above, one can observe that the System Default Customer is set to “YourStore Retail Account”. This is a Sage account exclusively for web store orders, and WH1 is the web store price list for that Sage account.